Respiratory mask



FIG. 1 is a rear perspective view, showing the new design for a respiratory mask;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof; and,

FIG. 6 is a right side view, the left side view being a mirror image thereof.

The broken line showing forms no part of the claimed design, and the shading is provided to illustrate contour only and is not an indication of texture, gloss, etc. 

CLAIM The ornamental design for a respiratory mask, as shown and described. 